Mapping the Potential for Development Near ‘L’ Stations

Do Chicago’s zoning rules position the city for transit-oriented growth?

Last week, Andrew Salzberg, a D.C.-based transportation consultant who works for the World Bank, posted a link on Twitter to a new map he’s created that overlays CTA rail lines and stations with how much development is allowed. It’s an attempt to show if zoning in Chicago is set up to concentrate development near transit.

Focusing development around rail stations curbs traffic and improves people’s mobility by increasing the number of destinations and services accessible by transit. It can also lower household transportation costs. People typically spend more on transportation than anything except housing, but as the Center for Neighborhood Technology’s Housing + Transportation Affordability Index demonstrates, living in a “location-efficient neighborhood” with lots of amenities and access to transit lets people spend less on transportation.

I emailed Salzberg to learn more about why he made the map and what he thinks it says about Chicago zoning and transit-oriented planning.

Steven Vance: What is the map showing?

Andrew Salzberg: The map focuses down on one element of zoning – maximum allowable FAR – and ignores all the other important variables (most obviously land use). This one indicator of density is then overlaid on the map of the CTA rail system.

[FAR, or floor area ratio, is the ratio of a building’s total floor area to its parcel’s area. For example, if a building occupied an entire parcel and was two stories tall, it would have a FAR of 2.0. The higher the FAR, the “denser” a building and neighborhood.]

SV: Why did you create it?

AS: The purpose of the map was to get a quick sense of the degree to which zoning in Chicago fosters higher development potential near transit.

SV: Have you made any observations about it? Done any analysis? What relationships are you seeing?

AS: A few things are immediately obvious – Chicago’s downtown core in and around the loop jumps off the page since zoning there allows for FARs over 10 – densities not approached anywhere else in the city. Chicago is pretty clearly a strongly monocentric city based on this map (although I have never actually had the pleasure of visiting). It also doesn’t take much to see how clearly focused the rail transit system serves this high density area.

It’s clear this is a pretty gross oversimplification of both zoning and transit service. On the zoning side, I’m only mapping the maximum allowable FAR for zones that have an FAR labeled in Second City Zoning’s fact sheet they put together on Chicago zoning. This ignores all the ways the other “non FAR” elements of the code can influence allowed density: limits on units per lot, minimum lot sizes, or setbacks, among other elements.

On the transit side the map presents elevated stations and lines, and completely ignores bus and Metra service. This is a quick shorthand for transit service that could definitely be improved. I’m working on a way to do a more comprehensive mapping transit service accessibility using Chicago’s GTFS files [schedules that allow Google Maps and other apps to provide trip directions] to get a more comprehensive measure of transit service across all modes.

Further out, at first glance, it’s not clear that areas within walking distance of transit are being “upzoned” to allow for higher densities – although I’d want to do more research to actually see if that’s the case. It looks like commercial corridors along major arterials are higher density (as high as FAR 3) than surrounding residential areas, but you can’t clearly see anything like a radial pattern of higher density around transit as you might in other contexts.

The final thing you notice is just how much of the city is made up of Planned Urban Development zones (PUDs) where the detailed design regulations are negotiated for individual plots of land.

SV: Where did you get the data?

AS: The data for the basic Chicago zones and transit data comes from Chicago’s great data program and the FAR for each zone comes from the hard clean-up work by Open City Apps.

Washington, D.C., supplies similar data – but it will also need some of the hard elbow grease to get the data cleaned up in the way the Open City guys did. I’m hoping to rally some people to that cause at Open Data Day in DC.

Chicago Zoning and Transit | MapBox
Salzberg's map shows opportunities outside the city core where zoning could be changed to allow for denser development near transit.
  • John

    Interesting. Overall it looks like the zoning was designed to match the existing conditions in an area rather than set as a goal for changing an area. Upzoning should definitely be considered in some areas, particularly where there is available transit capacity and where local business districts could use more local residents within walking distance for economic support.

  • nonya

    If I’m reading your description of FAR correctly, then I’m wondering how large portions of Lakeview and Lincoln Park are FAR 1. Most of the “less dense” areas tend to be 3 story buildings, be it a 3/6 flat or 3 story SFH or 3 story townhouses. I know they’re not usually taking up the whole lot, but they’re taking up well more than 1/3 of it. In the case of 3/6 flats or townhouses, probably close to 75%, SFH are probably a little less, more like 50-60%. Either way, you’re looking at a “reality” FAR closer to 2, not the 1 as shown on the map. So, does that mean that every new building in the area (and there are plenty from the bubble) has gotten a variance for FAR?

  • FAR isn’t my area of expertise. I’ll try to find someone to answer your question.

  • Joseph Musco

    nonya – It’s my understanding that FAR is a measuring stick within zoning regulations, not a zoning code itself. Single family homes have a low FAR. A 3-flat is zoned RT-4 with a FAR of 1.2. I live in an older multiunit RM-5 building that is 4 stories tall and has scores of small studios. It is listed as FAR 2 but if you took actual measurements the FAR would be much higher. According to the zoning law I just read (I’m no expert, just curious) actual structures can be a percentage greater or less than FAR before triggering review.

    Resources: Chicago Zoning Code summary
    http://www.clvn.org/pdf/zoningCodeSummary.pdf

    City of Chicago zoning code map
    https://gisapps.cityofchicago.org/zoning/

  • James

    I don’t even think “upzoning” is necessary if by “upzoning” they mean to rezone to a higher zoning district. I would think higher densities near transit lines/stations could be achieved by an overlay district that would allow higher FARs and reduce parking requirements. Using an overlay district would keep intact the desired use but allow more of it and I think it would help in a push for more transit oriented development.

  • Nonya – What this map appears to show is FAR as allowed by the current Chicago Zoning Ordinance. FAR is based on zone and lot size. For instance RS-3 zones (which is a typical single family zone) has an allowable FAR of 0.9. So a typical 25’x125′ lot could have a 2,800sf building placed on it. That doesn’t mean that there aren’t existing buildings which exceed the current FAR requirements, like the 3/6 flats you are mentioning that were likely constructed prior to the enactment of the CZO. All of this is separate from allowable density, which regulates the number of dwelling units you can build on a given site.

    The issue with this study though is the main driver for new residential development isn’t hampered by the allowable FAR or density but, in my experience, the minimum parking requirement. All new residential buildings require at least one parking space per unit. As you can imagine, the expense and feasibility of providing off street parking for new residential units does the most to limit density. I think a sound policy for increasing transit use would be a reduction or elimination of parking requirements for properties near transit stations.